This is an unofficial fix, if you care about your achievement tracking accounts validity, leave now, request a refund, and stop buying from this developer.
The author implemented achievements in his build 8336761645007378314 from 03rd of October 2017, but they were flawed since the timer was based on the time it took to draw on screen, thus never reaching the 1 second needed in between the achievements.
This patch is based on a reproduction of the original source code, which is included along with the binary.
You can download the source code and binary from Dropbox.
To apply the patch, unpack the downloaded file, and copy the /bin/Assembly-CSharp.dll file over the one in steam\steamapps\common\SpaceShot\SpaceShot_Data\Managed.
Now start the game and run any of the game modes. You can not idle in the menu, you lazy bastard.